The dark brown (?) one that starts in Vancouver, as long as I could sleep through the Newark stop. Some great Canadian cities, my native midwest American ones and it chugs through Russia where my grandparents were born. I would take a break in Amsterdam for, um, extracurricular activities

The Blue Line has the most stops so it's the best value. Plus it goes to Moscow and St. Petersburg so that would be a sacred pilgrimage for me as I visited the Holy Shrines of the Blessed St. Elena and her Divine Bangs.